1. Field of the Invention
The present invention relates generally to a picture transmission system, and more particularly to such a system for transmitting a video signal of compressed bandwidth over a communication channel and for receiving and processing the transmitted video signal.
2. Description of the Prior Art
Transmission of video data at reduced bandwidths has been the aim of many researchers in Government and private industry. Ideally, this reduction would come from the discovery and elimination of redundancy in the image. Practically, the data rate reduction comes at the expense of picture quality since identifying and coding the redundant parts of an image are rather complex tasks. This invention is primarily involved with the transmission of video data at a reduced data rate by first dividing the picture into discrete picture elements and then sending these picture elements at a reduced data rate. This method of sending specific picture elements at a reduced data rate has been investigated by other researchers. U.S. Pat. No. 3,309,461 issued on Mar. 14, 1967 to S. Deutsch and U.S. Pat. No. 3,342,937 issued on Sept. 19, 1967 to S. Deutsch use a pseudo-random sampling technique that allows the use of slow frame rates without the flicker effect one would ordinarily get with slow frame rates. More recently U.S. Pat. No. 3,769,452 issued on Oct. 30, 1973 to R. Stone expands on the Deutsch patent by making the pseudo-random technique compatible with normal fast scan television such as the NTSC standard television signal.
The principal disadvantages of the pseudo-random sampling technique are the poor resolution and intensity of the picture resulting from the small pinpoint samples that are projected onto the video screen. Additionally, the pseudo-random sampling pattern appears to crawl down the screen and detracts from the picture being displayed. Also, the picture quality is noticeably poorer than that of normal broadcast television and thus is unsuitable for use as its replacement.